Hydraulic Prop Underground Mining Support
Hydraulic Prop Underground Mining Support
Hydraulic props are primarily employed in slightly or partly mechanized coal mines, but are also found in ore mines, industrial mineral mines, etc
Extent of Mechanization:
fully-mechanized when serviced by a central pumping and distribution system for hydraulic fluid; not mechanized when serviced by a manual pumping system
(internal or external)
Form of Driving Energy:
electric or pneumatic pump for producing hydraulic pressure
10 - 15 sec. setting time Operating Materials:
oil in water-emulsion pure water
2 - 4 % oil in H2O, pH 5 - 8, dH up to 15
hydraulic props are primarily employed in slightly or partly mechanized coal mines, but are also found in ore mines, industrial mineral mines, etc.Even in fully-mechanized mines hydraulic props are still in use for special support, for example in areas of geological faults, at the ends of the face, face-roadway intersections, etc. due to their flexibility and versatility.
With conventional props, high pollution of mine water and drainage ways due to use of oil-in-water emulsion for hydraulic fluid. Glued - joint steel pipe props from Mingko use pure water as hydraulic fluid and thereby contribute to environmental protection.Lifespan:The long lifespan and suitability for reuse, in conjuction with the capability to replace defective components, ensure longlasting employment.
Hydraulic props consist of a sealed working cylinder with two valves, one for intake (setting valve) and the other for discharge (release valve, working valve) of hydraulic fluid. For increased stability the hydraulic props are equipped with a claw at the upper head-end and a base at the bottom. The function of the props is to stabilize incompetent roof or hanging wall. The positioned prop is telescopically extended by highly-pressurized hydraulic fluid injected by means of a setting gun and wedged into place with a specific setting load adjusted according to the respective compressive rock load. When the rated load is reached during installation or by subsequent strata movement, the working valve engages and opens the cylinder. This yielding prevents damage to the support from increasing compressive loading. The optimal support is attained when the props are installed in combination with articulated bars which distribute the forces over a wider hanging-wall or roof surface. During prop recovery, the release valve is opened with a key, allowing the hydraulic fluid to escape and the prop, equipped with a spring, to recede. The prop is then available for reuse.
AREAS OF APPLICATION:
Use of hydraulic single prop supports is only practical and economic where incompetent roof or hanging wall require a support method which can be adjusted to meet rapidly changing conditions. Hydraulic prop supports are appropriate for short-term installations involving frequent changes of location due to rapid face advance, or where high prop-setting loads are desireable. Such conditions arise in coal mining with roof caving or backfilling, in longwall mining, in room and pillar mining, as well as in ore mining by overhand stoping. In addition, single hydraulic props are suitable for support of all special mining activites such as support of fault-zones or roof-fall areas, machine rooms, and face-roadway
The use of single hydraulic props in the situations listed above can contribute significantly to protecting valuable natural resources by substituting for traditional timbering methods. Replacing the normally non-reuseable support timbers (e.g. in Turkey, totalling more than 1 m3/20 t of useable output) with re-usable props can also result in decreased operating costs.
The limited working length of the hydraulic prop, like mechanical friction props, is disadvantageous in mines with fluctuating seam or vein thickness.Due to the high setting load achievable with hydraulic props, capable of supporting areas 5 to 10 times larger than mechanical props, the prop density can be reduced.The Company is striving to adapt their products (individual props and articulated bars) to meet the demands of small-scale mining in developing countries:
- assembly and repair can be performed by local labor. The costs for an assembly and repair shop amount to only around 10 % of the costs of commonly
- the approx. 30 % net product arising from local production preserves the
country's foreign exchange position.
- cost savings of more than 50 % can be realized compared to the widely-used wood timbering.
- the capital investment for a highly developed and complex support system is not required.
- the use of glueable Joints in this modular system permits the replacement of damaged parts, therefore increasing the lifespan of the remaining components.
- storage costs are reduced by around 70 % as inventory can be limited to only a few standardized parts.Disadvantages of hydraulic props include high consequential or related costs for producing and distributing high-pressure fluids (pneumatic or electric high-pressure pump, liquid storage tank, high-pressure hoses, setting guns, etc.).
This disadvantage can be overcome by employing props which are set with manually-operated pumps. Such props were employed earlier in Germany, and are still used today in Anglo-Saxon countries. They function by using a hand pump to force the hydraulic fluid from the upper cylinder (storage cylinder)
into the lower cylinder (working cylinder), analogous to a hydraulic automobile jack.
SUITABILITY FOR SMALL-SCALE MINING:
The type of prop system employed affects the consequential costs. Simple manually-operated props offer an alternative to timbering in small-scale mines. The investment for single hydraulic props with an external pump system can only be recovered when large quantities are employed to
offset the higher costs for the necessary auxiliary installation devices.
|Model Item||Max height（mm）||Min.Height（mm）||Working Stroke（mm）||Rated working resistance KN||Weight （Kg）||Rated working Pressure MPa||Hydraulic pump pressure MPa||Setting load KN||Cylinder Dia. （mm）||Emulsion Liquid|
|DW06-350/110X||630||400||230||350||25||39.7||15-20||132-176||110||Emulsion containing 1% to 2% M10 emulsified oil|
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